WnAT IS A TONIC ? 
441 
not duly deprived of waste matters_, either of which interfered 
with nutrition ; or certain organs were left in a state of inac- 
tivity unnatural to them ; but whatever it may have been_, 
weakness and loss of substance generally tell plainly enough_, 
that the disease and its attendant circumstances have pre- 
vented the nutrition necessary to the preservation of tone and 
vigour being carried on. Now from the wonderful co-ordina- 
tion of the dijBferent parts of the system through which the 
exercise of the function of one influences that of others^ this 
general debility^ which commonly results from disease^ often 
disappears but slowly. Thus^ if the muscles of locomotion are 
so weak as to make their exercise painful^ the advantages of 
walking to the system generally are lost to it. Now that 
medicine which, without removing any cause of disease, aids 
the ordinary conditions of health in recovering the body from 
a state of debihty, and therefore of diminished tone, is a tonic. 
Other medicines than tonics may serve to remove debility 
when they can remove certain causes of it. Thus in those 
who, with feeble digestive powers, partake freely of rich and 
generous food, the blood and secretions become depraved, 
that is, charged with matters not fully suited for the wants of 
the system. These cases, which are extremely common, are 
attended with feelings of lassitude and debility such as are not 
to be removed by tonics, as is usually discovered by the suf- 
ferer, who, somehow, usually undertakes his own treatment 
by swallowing tonics before he seeks skilled advice. In such 
cases, alteratives and aperients, conjoined with modified diet, 
will serve to remove the debility without, or sometimes advan- 
tageously with, the assistance of tonics. 
The class of medicines ranked as tonics is a striking example 
of the difficulty which writers on classification of medicines 
seem to experience in deciding what characters are to be 
selected to distinguish one class from another. If it be asked 
is a glass of wine, or a tablespoonful of cod-liver oil, or a few 
grains of some medicinal preparation of iron, a tonic, a stimu- 
lant, or a food, the answer must be it is all three, for it gives 
strength and tone, it causes vital actions, it supplies where- 
with to nourish the body, that is to add material io the 
organism. We shall now take up this matter with a view of 
further elucidating the nature of a tonic, and, for this purpose, 
lay before our readers the relations of tonic, stimulant, and 
nutrient agents to each other. And, firstly, we shall treat of 
the relations of food and stimulants, so far as these bear upon 
those of either to tonics. 
Food serves two ends, — the one that of supplying substances 
in suitable form, from which our organisms may derive the 
materials necessary to make good the waste of tissue always 
